In program-controlled household appliances of the type to which the invention is directed, which include not only washing machines, but also clothes dryers, dishwashers and microwave ovens as further examples, the course of operation encompasses numerous individual steps, each of which may vary, usually in a multiplicity of parameters. This results in numerous possible programs, among which one optimal selection must be made at any particular time. Despite this, the program selection must not require excessive expense for functional components nor a training period, of any length worth mentioning, for the user of the appliance.
In German Auslegeschrift No. 26 50 964, a program input device is described for electronic control devices, which permits the setup of a machine program which comprises a plurality of program sets which are performed in sequence. This programming, as provided for in this known device, is accomplished with the aid of addresses encoded as numerals on a display board which is integral with the device. First, the code for the first program set is read off on the associated display board. Then an appropriate address key is pressed and simultaneously, via a separate numeral keyboard, the appropriate numerical code is inputted. This numerical code is then displayed in numerical form by means of a luminous indicator associated with the particular address key. The next subsequent address key is thereupon pressed for a further program set and the appropriate numerical code is inputted via the numeral keyboard, which code is then also displayed. The programming is continued in this manner until all the digit locations for all the program sets are occupied or programmed in.
Such a programming method does offer a high degree of freedom of choice in setting up programs. However, this is attained at a very high cost for the functional components in the form of a double keyboard with address keys on the one hand and a numeral keyboard on the other. Beyond this there is no security against programming errors, so that the user of the appliance first must become experienced in the programming and second must always pay close attention to what he is doing. Both these requirements, however, run diametrically counter to the desire for a largely automatic mode of operation such as a typical for the household appliances with which the invention is associated.